Electron discharge device circuits



Aug. 18, 1942- A. M. SKELLETT ELECTRON DISCHARGE DEVICE CIRCUITS Filed March 2, 1940 .3 Sheets-Sheet 1 FIG.

FIG. 3

COLLECTOR FLOA TING ANODE INPUT CONTROL GRID T m a k m5 M A COLLECTOR GRID TTiZNE Y A. M. SKELLETT ELECTRON DISCHARGE DEVICE cmcurrs 3 Sheets-Sheet 2 Filed March 2, 1940 [5050 I70 I80 I90 10 so 50 10 do 90 lboflolzo laol I50l6 I70 I00 I90 T n R mu E V w AV. .8

M .5" f ATT NEV A. MqsKELLE'TT ELECTRON DISCHARGE DEVICE cmcux'rs Aug. 18, 1942.

Q 3 Sheets-Shea: 3

Filed March 2, 1940 //s V V V PL A TE FIG. 8

FLOATING moo:

GRID VOLTAGE "/M/ENTOR ALMSKELLETT er Y ATT' RNEY being realizable in a single device.

Patented Aug. 18, 1942 ELECTRON DISCHARGE DEVICE CIRCUITS Albert M. Skellett, Madison, N. 1., nlllgnor to Bell Telephone Laboratories,

rated,

New York, N. Y.. a corporation or New York Application March a, 1m, SerinLNo. 321,852

18 Claims.

This invention relates to electron discharge devices and, more particularly, to a vacuum type electron discharge device and to circuits incorporating the latter.

Vacuum type electron discharge devices are known that may be utilized for amplification, detectionymodulation. or oscillation, and the like purposes, one or more of such functions even Other electron discharge devices are known which contain a small amount of gas, space current in which flows upon ionization of the gas and ceases upon deionization of the gas. These latter devices have an off-and-on, blocked and unblocked, operate and non-operate, or trigger characteristic. A device which combined the features of the vacuum tube and the gas-filled tube or so-called thyratron, without the limitations of the latter would meet a need in the electron discharge device fleld.

An object of this invention is to provide a vacuum tube structure that will satisfy this need, and circuit arrangements most simply and emciently utilizing the characteristics of such a device.

a In accordance with the invention, the conventional triode or multigrid vacuum tube is modified to include certain auxiliary electrodes, and to hav'eits anode provided with an aperture to permit a preassigned percentage of the electrons originating at the cathode or filament to pass through. The auxiliary electrodes comprise a deflector member 'or plate, a secondary electron collecting grid, and a secondary electron emitting anode. The auxiliary anode is positioned out of the straight-line path of particles thrown out by the cathode which would contaminate the secondary electron emitting surface, such particles being collected by the deflector which causes the primary electrons passing through the .primary anodes aperture to be deflected and to travel through the collector grid and against the auxiliary anode.

The current-voltage characteristic of the auxiliary anode is-such that a zero-current condition exists at a high and ate. relatively low potential on that anode. If the latter is at the higher zero-current potential, the external circuit therefor may be disconnected and the anode will "float'at this potential in a stable manner; at the lower zero-current potential, however, the equilibrium is unstable and, lithe external circuit is disconnected, the potential falls either Way, i. e., the anode returns to a condition of or near zero potential or rises to the second zerocurrent potential and is stable thereat.

The modified vacuum tube, 1. e., trlode, or tetrode or other multigrid tube, in accordance with the invention, will evidence trigger action with substantially no change in the other characteristics of the device as an amplifier, modulator, demodulator or oscillator, as the case may be. The external circuit is such, preferably, that the cathode and the emission anode are connected through a resistance and source of'negative potential, the control grid is connected to a point on that resistance and initially biased to beyond primary anode current cut-oil, the emisto its high and stable zero-current potential, the

control grid having its negative bias further reduced. Alternatively the emission anode may initially be at or above its low zero-current potential, the control grid biased to beyond primary anode current cut-off, and a pulsing circuit be associated with the control grid to reduce the grid bias to above cut-off, the flow of primary electrons causing a rapid rise of the auxiliary anode to its high and stable potential, and the grid being driven even more positive. Obviously, the tube could originally be functioning with input grid control of the primary anode current and variations therein, and a circuit be associated with the control grid or emission anode to trigger-oi! the tube.

A more complete understanding of this invention will be obtained from the detailed description that follows, taken in conjunction with the appended drawings, wherein:

Fig. 7 shows another circuit arrangement embodying the invention;

Figs. 9, 10, 11 and 12 show a pulse counting, an oscillator, a pulse inverting and a multivibrator circuit, respectively, embodying the invention; and

Fig. 13 shows a circuit arrangement embodying the invention, and in which the deflector electrode of the discharge device is utilized as a control electrode.

With reference now to the drawings, the structure of the electron discharge device or vacuum tube in accordance with this invention, will be evident from Figs. 1, 2 and 3.

The discharge device It comprises an evacuated envelope or enclosure II, for example, of glass or other suitable material, having a reentrant portion l2 terminating in a press I3;

and a base II, which may be of insulating material, and which supports or carries a plurality of contact pins or prongs ii on which are terminated the external ends of the wires or leads l8,

embedded in the portion l2 and adapted for conductive connection to the electrodes of the device.

The electrodes comprise a cathode ll; an inner or input control grid ill; a primary anode IS; a deflector, reflector or guide member, plate or electrode 20; a secondary, auxiliary or collector grid 2|; and an auxiliary, secondary electron emitting, or floating anode 22. These electrodes are mounted between a pair of spacers or discs 23 of insulating material, for example, mica, spaced apart by supporting rods 24, extensions 25 of which are united to a collar or clamp 26 securely engaging the portion l2. The electrodes are supported in preassigned position, intermediate the discs 23 and relative to each other, by the supporting rods 21, which extend through and make extremely tight fit with apertures or slits in the discs. The getter 33, for flashing in the tube to remove residual gases after the pumping operation, may be mounted on a suitable support 34 depending from one of the extensions 25.

The cathode I1 is of the equipotential type and may comprise a cylindrical metallic sleeve, speciflcally, nickel with an outer surface of barium and strontium oxide constituting a source of primary electrons when the cathode is heated. The metallic sleeve is fastened onto a cylindrical quartz tube that extends beyond the ends of the'sleeve; a heater wire, for example, of tungsten, the ends 28 of which are to be seen in Fig. 1, for indirectly heating the cathode, is threaded through this tube and connected at its ends-to a pair of the leads IS. The cathode is connected to the heater wire by a short connection 29. Of course, a filamentary type cathode could be used.

The input control grid l8 surrounds and is coaxial with and spaced from the cathode, and comprises a pair of axially extending frame members on which a large number of turns of closely spaced, flne wire is securely wound.

The primary anode l9 comprises a metallic cylinder, for example, of nickel, and open at each end, that surrounds and is spaced from the grid and is coaxial with the latter and with the cathode. The anode is provided with an aperture or elongated slot 30 that permits a preassigned percentage, for example, ten per centum, of the electrons emitted by the cathode to pass through.

The deflector 20 comprises an arcuately-shaped metallic sheet, for example, of nickel, spaced from the anode l3 and so disposed with respect to the aperture 30 in the latter that the electrons passing through the aperture are directed toward the deflector, which may be electrically connected through tie-wire 3i to the cathode and, therefore, would be at cathode potential. This deflector causes the electrons that pass out through the aperture 30 to follow trajectories of the character indicated by the dotted lines of Fig. 3, and to pass through the collector grid and to impinge on the secondary electron emitting anode. The secondary electron emission surface of the auxiliary anode is maintained free of contamination by particles from the cathode, because such particles travel in straight lines, and will deposit on the deflector where they can do no harm. Although the deflector is shown connected to the cathode within the envelope ll it could be brought out to a separate terminal, and, if desired, connected to a source of potential. a

The collector grid 2| comprises an elongated, rectangular wire frame member 32 including a plurality of wires 35, spaced apart and arranged in parallel to one another and to the long edges of the frame, and disposed paraxially of the tube and in a plane at a substantial angle-of the order of 30 degrees-t0 a plane extending at right angles to the spacers and through the electrode assembly along the line A-A of Fig. 2, a paraxial plane through the center of the cathode and the center of the window in the flrst anode. The collector grid includes a planar metallic or shield portion 36, spaced from the anode l9 and extending substantiallyat right angles to the rest of the grid and outwardly toward the envelope. In another tube constructed in accordance with this invention, the collector grid comprised a pair of wire supports extending paraxially of the envelope and a plurality of short, parallel, spaced wires extending between the wire supports and at right angles to such supports; and a shield portion similar to portion 36 was provided at each outer edge of the grid, for example, as shown in Fig. 3A.

The auxiliary anode 22 comprises a planar metallic member, for example, of copper, disposed within the angle formed by the collector grid and its shield portion, substantially parallel to the plane of the grid wires. The surface of the anode 22 opposite the collector grid has a good ratio of secondary to primary electrons, for example, a barium-magnesium oxide surface. The surface may be prepared by flashing a bariummagnesium getter button in front of the copper plate in a vacuum. This leaves a clean surface of pure metal. The evacuated enclosure is then opened to air, and the surface immediately oxidizes. The oxidization period preferably is restricted so that only the surface portion ofthe metallic layer deposited is oxidized. The flnal layer then comprises a surface portion of magnesium oxide and barium oxide and a sub-layer of magnesium and barium. During operation of the devicesome of the magnesium and barium may diffuse into the surface portion. The plate is then mounted last, in the tube structure of the device It. The ratio of metals evaporated is approximately 25 per cent barium and 75 per cent magnesium by weight. With such an auxiliary electrode, it has been found that a secondary to primary electrons ratio of unity is obtainable with primary velocities of only 30 volts or less.

The device I0 may be utilized as an amplifier,

a detector, an oscillator or a modulator. It also has the characteristic that it may be rendered operative or'non-operative for such uses substantially instantaneously as the result of applying to or removing a control potential from the auxiliary anode, or the input control grid. In this latter respect, the-device is similar to the socalled gas-filled tube, without the limitations oi the latter. With a gas filled tube, ionization of the gas must occur before space current is established, and deionization ,must occur before the space current it One type of gas-filled tube is the hot cathode tube, in which, so long as the input control grid is maintained sufllciently negative with respect to. the cathode, ionization will tive in potential and will thus be brought back to equilibrium. Conversely, if it starts to drift up in voltage, the potential difference between it and the grid will be decreased, and fewer secondarieswill-be drawn across, thereby decreasing its potential by the accumulation of more nega-.

v tive charge.

of the first zero is, therefore, determined pri- 'marlly by the secondary to primary ratio of the Similar reasoning will explain the instability of the first nero, except that, whereas, for the second zero, the number or secondaries which'are eifective is that drawn ofl bythe potential difference between the collector grid and floating anode, for the first zero, all of the secondaries -are.drawn across and the true secondary to primary ratio is the important factor. The voltage surface of the floating anode, and is thus approximately the'same for all values of collector I grid potential, but the voltage of the second zero is determinedprimarily by this potential and the geometry of the collector grid and floating anode structure of the tube.

tube, the noise introduced into the associated circuit by such devices, the changes in the gas content during the life of the devices and their limited application other than in the control or pulsing circuit fleld, constitute some of the limitations'aifecting the usefulness of gas-filled tubes.

With the device of this invention, there is no gas to be ionized or: deionized, and none of the attendant limitations resulting from its presence. Furthermore, after the device has been'rendered operative or triggered-on," the space current is and remains under control of the input grid until the device is triggered-oil"; that is, the device may be employed in the usual way in which the conventional three-element vacuum tube or triode would be. This is true, also, of the tetrode and pentode or other multigrid tubes, modified to in-. clude the deflector electrode, collector grid and secondary anode and the apertured primary anode. v a

The "trigger"action of the device It depends on the floating properties of the auxiliary anode. Fig. 4 shows a family of current versus potential characteristics of this floating anode for a tube constructed in accordance with the invention.

The diflerent curves correspond to different potentials on the collector grid. As the potential is increased, the current passes through the zero axis twice. At each of these two points, the number of primary electrons is equal to the number of secondaries which are drawn oil the surface.

If the floating anode is at the higher zero potential, the external circuit may be entirely disconnectedand the element will float in a perfectly stable manner at this voltage. At the lower zero potential, however, the equilibrium is unstable and if the external circuit is disconnected the potential will fall either way. If it falls'down, the element returns to zero, and, if it falls up, it jumps to the second zero potential and floats stably there. v 7

To understand the reason for this stability, it is only necessary to consider the conditions affecting the addition or removal of charge from the floating anode. Suppose that initially this element is floating at the second zero, and that it starts to drift lower in potential. The voltage difi'erence between it and the collector gridwill increase and more secondaries will be drawn The curves of Fig. 4 were taken with the first anode current approximately constant at 4 milliamperes. It was adjusted to this value at the start of each curve and changed very little. 7 The first anode was held atvthe potential of the collector grid. -Fig.- 5 gives similar characteristics, but with the difference that the-control grid potentialwas held constant 'at -12 volts for all curves. It indicates the constancy of the first zero potential under different conditions.

If the floating anode is connected to ground zero point or stable floating potential is reduced.

The floating anode will now floatat a potential slightly less than it did when free. This new floating potential is determined by the intersection of the I- V characteristic with the line, whose slope is equal to the load resistance. For example, the dotted lines R1 and R: of Fig. 4 have the slopes of one megohm and two-tenths megohm respectively, and the potentials of'the points at which they cross the curves are the floating potentials for these resistance values. Resistances smaller than about 1.4)(10 ohms do not intersect the curves at all, and the critical resistance is therefore near this value. It is given by the formula so that, in general, we have that R T;- where Em and Im are the voltage and current of the negative maximum of the characteristic. The floating anode will not float atvalues of'reslstance less than R0 for then the number of electrons supplied via the resistance will be in excess of the numbcrof secondaries needed to maintain the effective secondary to primary ratio at a value equal to unity, and the floating anode will simply charge up negatively and its-potential will be brought to zero.

These principles are utilinedto get oii and on,

or operate and non-operate, or block and unaway from it. It will, therefore, go more posiblock, or trigger" action in a vacuum tube.

i'ormer T1, the other end of the secondary winding being connected to a contact engaging theresistance R and dividing it into two portions R1 and R2. The primary anode I9 is connected with the cathode through the primary winding or the output transformer T2 and the source, for example, a battery B, of anode potential. The deflector 20 is connected to the cathode, and the collector grid 2| .is connected to the high potential terminal of the battery B. The values of R1 and R: are such that their total adds up to a value greater than Rs, preferably considerably greater, one tofive megohms being suitable.

Suppose that the cathode heater is turned on, and brought to operating temperature. The

floating anode and the inner grid will all be at the negative potential, and no electrons can flow through the tube. If, now, the potential of the floating anode ls momentarily raised to a value greater than the first zero potential (Fig. 4) by application of the necessary potential between terminal A and ground, for example, from the pulsing source S, the potential of the grid will be raised a few volts because of the drop across R1 and R2, and a small electron current will flow through the tube. As soon as electrons flow to the floating anode, its potential will jump to the second zero voltage carrying the grid bias up to the operating point. The tube has then triggered-on or fired, and can be utilized, for example, as an amplifier, through the transformers shown.

It can be triggered-oil by decreasing momentarilythe potential of the floating anode to a value slightly less than the first zero value, or by sending a negative pulse into the input or grid circuit, 1. e., through the transformer T1,

of sufiicient value to momentarily cut oil the electron fiow. The triggering pulses to the floating anode may be applied through a suitable condenser Ci.

Fig. fl is similar to Fig. 6 with the additionof Ra, and the omission of the pulsing source S and the condenser C1. R1, R2 and R3 form a bleeder resistance across the total supply battery maintaining the floating anode at a potential slightly through B: when the tube is off.

Now it, through the input transformer, a positive potential, for example, of a volt or two, is

impressed on the grid, enough electrons (less 1 than a. microampere) will be passed to trigger the tube on; the floating anode will jump to the second zero as in the case of the circuit of Fig. 6. The circuit of Fig. '7 thus has an advantage over that of Fig. 6 in that considerably smaller voltages serve to trigger it on. It may be triggered-ofi by applying a negative signal or pulse in the grid circuit great enough to cut off momentarily the electron stream.

Fig. 8 shows an operating characteristic for the circuit of Fig. '1. A positive potential of 1.2 volts appliedbetween the junction of R1 and R:

and the control grid triggers the tube on and ating characteristic, or from zero to 7.75 milli-- the plate current jumps to point Q on the operamperes. Positive or negative potential may then be applied, and the plate current will swingup and down as in an ordinary amplifier tube. It a negative potential greater than 10.3 volts is applied, the tube will trigger-ofl-as shown. A

' Fig. 6, and then choosing a value for R: such I that the junction OI-RI and R: will have a potential, with no electrons flowing in the tube, slightly greater than that of the first zero of the characteristic (Fig. 4). Obviously, Ra need not be connected to-the highest potential of the-power supply.

The tube in the circuit of Fi 7 is equivalent in most respects to a hot cathode thyratron." These differences may be noted, however. Since there is no deionization time limitation, the vacuum tube may be made thousands of times faster than the thyratron. 'The vacuum tube may be extinguished" or triggered-off by a negative voltage on the grid; while the tube is on, itis not noisy like the gas-filled tube, and its grid maintains complete control over the space current for amplification, oscillation, detection, modulation, etc. The gas tube may be replaced in'many of its applications by the device I0, e, g., in pulse counting, oscillator, pulse inverting and relay circuits.

Fig. 9 shows a circuit arrangement for measuring or counting the number of pulses originating in a source S, e. g., for counting the number of alpha particles given off by a radioactive substance. The circuit comprises three counting stages A, B, C, each of which comprises an electron discharge device I0 of the type already described in detail hereinabove.

Each secondary anode is connected to the pulse input terminal through a condenser and the common condenser BI. The collector grid and the primary anode.oi each tube are connected together and to the high potential terminal of a source 92 or anode potential, which may be common to the tubes I0, a register or counting device or mechanism It being connected between the potential source 92 and the primary anode of stage C. Each cathode is connected to ground, which would permit, if desired, the electrodes of the three devices I0 to be enclosed in a single envelope. Each input control grid is connected through a network I00, comprising a resistance IM and condenser I02 in parallel and a condenser I03 to a sliding contact I 04 engaging the resistance I05 which is connected in series with a condenser I06 between ground and the junction of pulsing input circuit resistance I01 and condenser 9|. Each secondary anode is connected through series-connected resistances I08, I09 and-network I I0, comprising resistance III and condenser II2, to the negative terminal of potential source H3 that normally provides a preassigned negative bias on the input grids and normally maintains the emission anode at a potential below its low zero-current potential. Each input grid is connected to resistance I09 through its network I00 and a sliding contact III that engages the resistance I00. Each emission count the number of impulses or pulses appear ing between the input terminal and ground and originating in the source S. The contact I! is at such a position that that portion of the initial impulse applied to the grid through the condenser I03 andnetwork I00, simultaneously with the application or the pulse to the secondary and network I 0 oi" anode through the condenser 00, causes the grid to rise to a potential above primary anode current cut-oft and the rise of the secondary anode to its floating potential, as already outlined heretofore with particular reference to Fig; 6. When the tube of stage A becomes operative or fires," th tube of stage 13 is primed so that it will operate or be made conductive by the next pulse applied at the input terminal or the counting circuit. This priming results from the potential built up across the network III! of the grid circuit of stage B. When the next pulse is received, the tube I0 01 stageB becomes operative as did that of stage A and primes the succeeding tube for the succeeding pulse. With tube I0 of stage A on, the pulse that operates the tube of stage B is enough to swing the inputgrid of stage A positive so thatit draws current. This charges condenser I02 so that, alter the pulse ceases, the discharge 01 this condenser through its associated resistance IOI swings the input grid to below primary anode current cut-oi! andoauses the tube or stage A to be extinguished. The next impulse causes the tube 01' stage C to become cona condenser C10 is connected between the cathode I1 and the first or primary-anode II.

Let it be assumed that the condenser C10 is un-.

charged, as a result or open switch means (not shown) in the lead between R: and battery C and between resistor R4 and battery B, i. e., when the circuit is not being used. Closure of such switch means would provide the closed circuit shown in condition for oscillation generation, and initiate such oscillations. Current flowing from battery B through resistor R4, into the condenser C10 charges it and raises the potential of that side or the condenser connected to the primary anode. When, as a result of such potential increase, the anode I 0 reaches a sufllciently positive potential,

the control grid potential will not be suincient to prevent the flow of electrons to the primary anode. The flow of electrons starts or "ilres the tube in the manner described with reference to Fig. 7. The grid potential swings from near cut-oi! to the region zero potential so that the greatly increased ele"tron flow causes the discharge of condenser Clo, eflectively bringing both sides or the condenser 010 to nearly ground potential once more, and lowering the primary anode potential to a value at which the electron stream is blocked or the tube extinguished. The process then repeats itself, the condenser being charged slowly and discharged rapidly, resistor R4 being of such value that the current during the charging period is less than that which flows through the tube to discharge the condenser.

The frequency of the oscillations, of a sawtooth character, is dependent in part, at least, upon the time constant of the circuit defined by the resistor R4 and condensor C10. Actually, the condenser C10 is never fully discharged, but the positive side oi it is reduced to a value so low that the primary anode potential is not sumcient to enable electrons to flow through the device I0.

A condenser C20 may be connected between the control grid I8 and the secondary anode 22, and in parallel with resistance R1. This condenser causes the control grid to go positive more rapidly than when it is not added to the circuit, and,

hence, enables a higher rate oioscillation to be obtained. The collector grid 2| is shown connected to the primary anode. An alternative So long as pulses continue to be applied to the circuits input terminal, the tubes will operate around the ring and the register indicate each.

I or course, registering or indicating mechanism could be associated with each device I0, and any desired number of stages may be used, a threestage, single register pulse counting circuit being shown by way or illustration. Since the initial position of contact I04 on resistance I05 was to compensate for the absence initially of a priming potential across the resistance III of the network H0 in stage A, after the first tube has become conductive, contact I 04 may be adjusted to a preasslgned position such that until the network IIO does prime the tube or stage A, the pulse succeeding the initial one is not suilicient to render stage A conductive after its extinguishment as a result of the second pulse and operation of stage B.

Fig. 10 shows a relaxation oscillator circuit embodying the invention. It will be observed that the circuit is similar to that of Fig. 7 except that the input transformer T1. is omitted, the output transformer is replaced by a load resistor R4, and

arrangement is to connect the collector grid to a could be connected directly to the positive terminal or the source B. The potential of the collector grid, in the latter case, does not swing or vary with variations in electron currents.

Fig. 11 shows a pulse inverting or inverter circuit embodying the invention. It comprises two discharge devices I0, such as are included in the previously described circuits. The cathodes are connected together and to ground, with the deflector plates connected to the cathodes of their respective tubes. Each primary anode is connected through a load L to the positive terminal of an anode potential source B, the negative terminal of which is connected to ground, and the primary anodes are directly connected through a condenser C30. Each collector grid is connected to its respective primary anode; although it may be connected directly to the potential sourceB', so that its potential does not swing with variations in the electron currents. The source C oi biasi g potential tor the control grids is connected between ground andthe junction of resistances P1, P2, the outer ends of which are connected to the secondary anodes. The control If the biasing potential source 0 is suiiicient to maintain the control grid at a potential of a value corresponding to that in the working range of the structure determined primarily by the cathode, control grid and primary anode, there will be certain amount of electrons flowin to the secondary anode, and by virtue of this, its potential will be at a value between the first br lower zero-current potential and the potential bf the primary anode and the collector grid. If

the potential of the control grid starts to drift potential, and an electron stream is maintained between the cathode and primary anode; and that the tube E is blocked or "extinguished. Assume, then, that a positive pulse is impressed on the terminals 40, and is of such a value that it elevates the potential of the secondary anode of tube E above its lower zero-current potential. As the secondary anode of tube D is already above that potential, the incoming pulse has little or no effect on the tube D. The control grid of tube E is driven in the positive direction and the tube E is caused to fire in the same way as the tube of Fig. 6. As the tube E becomes operative, its primary anode swings negative, and this negative swing is transmitted by the condenser C30 to the primary anode of tube D decreasing its potential to such an extent that primary electrons are no longer enabled to flow in tube D, and the latter is extinguished. The next positive pulse received at terminals 40 causes tube D to become operative, and causes tube E to return to its initial inoperative condition. Thus, a series of positive pulses transmitted through the terminals ill will alternately operate the tubes D, E.

Fig. 12 shows a multivibrator circuit embodying the electron discharge device I ll of this invention. The control grid is connected through a resistance Rs and source C of biasing potential to the cathode and ground. The cathode is connected to ground and has the deflector plate tied to it. The collector grid and the primary anode are connected together and, through load resistance R1, to the high potential terminal of source B of anode potential, the low potential terminal of source B being connected to ground. The secondary or floating anode is connected to an intermediate point on potential source B through a resistance Re, and to the control grid through a condenser C40. The collector grid, as in previously described circuits, may be connected directly to the source B of potential so that it does not swing with variations in the electron currents.

The floating anode has a current-voltage characteristic such as is shown in the curves of Fig. 4, and, by virtue of the secondary emission from its surface, its potential increases with increasing primary electron flow to it. This follows, of

course, provided that its potential has been raised to a value in excess of the first or lower zero- -current potential. Above such a potential, the

potential of the floating anode increases positively for positive increases in the magnitude of the primary electron current, and, thus, also, for positive increases in the potential of the control grid. The resistance Re couples the secondary anode to the source B to maintain the secondary anode. with no current flowing thereto, at a potential in excess of the low zero-current potential. The resistance Rs should be of such magnitude that the potential on the control grid varies in response to. the impulses it receives through condenser C40 from the secondary anode.

in a positive direction, there will be an increase in the amount of electron flow to the secondary anode, and, hence, an increase of its potential in the positive direction. This latter increase is communicated through condenser C40 to the control grid to drive it still further in a positive direction to cause a further increase in electron flow to the secondary anode, and a further increase in the control grids positive potential. This process is regenerative and the potentials of the floating anode and the control grid will swing to the limit in a positive direction. Thereafter, they will start to drift in a reverse direction and by the same process in the reverse sense, the potentials will swing as far negative as possible. This process will be repeated, the frequency of oscillations being determined by the time constants of the circuit elements.

Fig. 13 illustrates another feature of the invention. This circuit is the'same as that of Fig. 6, except that the deflector member 20 is connected through the source of adjustable potential to ground, rather than directly to the cathode. With this arrangement, the deflector may be adjusted to a potential diflerent from that of the cathode. For example, after the device In has been caused to become conductive in the manner outlined with reference to Fig. l, the deflector may be adjusted to a negative potential sumcient to prevent enough electrons to reach the anode 22 to enable the latter to remain above its low zero-current potential, whereby the grid potential is reduced to a value below primary anode cut-oil, and the device rendered non-conductive or extinguished. Instead of the battery 80, or in addition to it, a circuit element,

e. g., a network or an impedance, more specifically, a resistance 8|, may be connected between the deflector '20 and ground, or between the battery 80 and the deflector 20, and uni-directional or alternating signal energy applied to the impedance to alter the potential of the deflector with respect to ground and to control the electron current in a preassigned manner.

Although this invention has been disclosed with reference to various specific embodiments, it will be understood that it is not limited thereto, but by the appended claims only.

What is claimed is:

1. In combination, an electron discharge vacuum tube comprising acathode, an anode, and a control grid intermediate said cathode and anode, an input circuit coupled to said cathode and grid, an output circuit coupled to said cathode and anode, and auxiliary electrodes in said tube, one of said auxiliary electrodes comprising a deflector electrode for deflecting onto another of said auxiliary electrodes primary electrons from the electron stream established between said cathode and anode, said second auxiliary electrode being treated to emit secondary electrons in such ratio as to rise to a floating stable potential, and a circuit connection between said second auxiliary electrode and said grid.

2. In combination, an electron discharge vacuum tube comprising a; cathode, an anode and a control grid, an input circuit coupled to said cathode and grid, an output circuit coupled to said cathode and anode, auxiliary electrodes in said tube and including a deflector electrode for deflecting primary electrons onto another of said auxiliary electrodes, said second auxiliary electrode being adapted to emit secondary electrons in ratio greater than unity and having a currenta voltage characteristic such that it has zero current at a high and a low potential more positive .than said cathode, a connection including a resistance between said second mentionedauxiliary electrode and said cathode, a connection unblockingthe electron stream to said second and fourth electrodes.

6. An electron discharge device circuit comprising a vacuum tube having an electrode constituting a source of electrons, a second electrode for receiving said electrons, a third electrode intermediate said first and second electrodesfor regulating the electron flow therebetween in accordance with signal variations impressed on said third electrode, a fourth electrode having a'secondary electron emission surface for receiving a preassigned portion of'the electrons from said first electrode but located outside of their normal from said resistance to said grid, means for bias- 3.In combination, an electron discharge device comprising a cathode, an input control grid, a primary anode having a passage therein for a portion of the electrons passing thereto from said cathode, an auxiliary grid, an auxiliary anode and an electron deflecting electrode, said auxiliary anode being an emitter of secondary electrons in ratio greater than unity when bombarded with primary electrons, said deflecting electrode directing onto the auxiliary anode the electrons that pass through the primary anode, an impedance and a source of control grid biasing potential connected in series between said cathode and said auxiliary anode, a connection from said impedance to said control grid, a source of potential connected between said cathode and said primary anode, and an impedance connected between said auxiliary anode and said primary anode potential source.

4. An electrical circuit comprising a vacuum tube having a pair of electrodes between which a stream of primary electrons may be established, an auxiliary electrode having a preassigned floating potential while said electron stream flows, and a control electrode between said pair of electrodes, impedance means connecting said auxiliary electrode and that one of said pair of electrodes with which the electron stream originates, and a connection from said impedance means to said control electrode for biasing it to a potential above that at which the electron stream would be blocked, while said auxiliary electrode is at said preassigned potential.

5. An electron discharge devicecircuit comprising a vacuum tube having an electrode constituting a source of electrons, a second electrode for receiving said electrons, a third electrode intermediate said first and. second electrodes for regulating the electron flow therebetween in accordance with signal variations impressed on said third electrode, a fourth electrode for receiving a preassigned portion of the electrons from said i first electrode but located outside of their normal paths, a fifth electrode for deflecting said preassigned portion of electrons from'their original paths to said fourth electrode, and means including said fourth electrode for blocking and paths,.a fifth electrode for deflecting said preassigned portion of electrons from their original paths to said tourth electrode, a sixth electrode constituting a secondary electron collecting electrode, and means including said fourth electrode for blocking and unblocking the electron stream to said second and fourth electrodes.

7. An electron discharge device circuit comprising a vacuum tube having an electrode constituting a source of electrons, asecond electrode for receiving said electrons, a third electrode intermediate said first and second electrodes for regulating the electron flow therebetween in accordance with signal variations impressed on said third electrode, a fourth electrode for receiving a preassigned portion of the electrons from said first electrode but located outside of their normal paths, a fifth electrode for deflecting said preassigned portion of electrons from their original paths to said fourth electrode, and

means including said deflecting electrode for a passage therein so that a preassigned portion of said electrons may pass through, a control electrode between said electrodes for regulating the flow of electrons therebetween in accordance with signal variations impressed on said control electrode, a secondary emissionlelectrode for receiving said preassigned portion of said electrons, a secondary electron collecting electrode, a deflectingelectrode for deflecting said preassigned portion of electrons onto said emission electrode, means for connecting said emission and control electrodes and for placing a preassigned biasing potential on said control electrode, means for maintaining said collecting electrode and said second electrode at preassigned potentials, and means for altering the potentials on said control and emission electrodes so that the control electrode is at a potential that does not block electron flow to said second electrode.

9. An electrical circuit comprising an electron discharge device having a pair of electrodes between which a stream of primary electrons may be established, an auxiliary electrode constituting a source of secondary electrons and activated by some of the primary electrons, an electrode for deflecting said primary electrons onto said auxiliary electrode, and means forimpressing a potential on said deflecting electrode to block passage of primary electrons to said auxiliary electrode.

10. The combination of a source of electrical pulses and a circuit for counting the number of pulses originating in said source, said circuit comprising a plurality of vacuum electron, discharge devices connected in tandem, each of said 11. An electric discharge vacuum tube comprising a cathode, an anode for receiving primary electrons from said cathode, an auxiliary anode positioned to be bombarded by some of said primary electrons, and adapted to emitsecondary electrons in ratio greater than unity whereby said auxiliary electrode rises to and floats at a stable potential, and a grid biased negatively with respect to said cathode and positioned in the stream of electrons bombarding said auxiliary anode, and means connecting said floating anode and said grid.

12. In combination, an electric discharge "Zyacuum tube comprising a cathode, an anode for receiving primary electrons from said cathode, an auxiliary anode positioned to be bombarded by some of said primary electrons and adapted to emit secondary electrons in ratio greater than unity whereby said auxiliary anode rises to and floats at a stable potential, and a grid biased negatively with respect to said cathode and positioned in the stream of electrons bombarding said auxiliary anode, and means providing a direct resistive connection between said floating anode and said grid.

13. In combination, an electric discharge vacuum tube comprising a cathode, an anode for receiving primary electrons from said cathode, a control grid between said cathode and anode, and an auxiliary anode positioned so as to be bombarded by a-portion of said electrons when electron flow occurs between said cathode and said first anode, said auxiliary anode being adapted to emit secondary electrons in ratio greater than unity, means for biasing said grid to a potential such as to block electron flow between said cathode and anode, means connecting said grid and said auxiliary anode, and means connected to said grid and said auxiliary anode for momentarily reducing the grid bias so that electrons flow to said auxiliary anode whereby secondary electron emission by said auxiliary electrode raises the latter to a floating stable potential thereby maintaining the bias on said grid above electron blocking potential until the potential on said grid is momentarily reduced to a value blocking electron flow between said cathode and flrst anode.

14. In combinatioma source of electrical pulses and a circuit for indicating the number of pulses originating in said source, said circuit comprising a plurality of interconnected vacuum electron discharge devices, each of said devices comprising a pair of electrodes between which an electron stream may be established and a secondary electron emission electrode, means responsive to one of said pulses and connected with one of said pair of electrodes and with said secondary electrode of one of said devices for estabmean? lishing primary and secondary electron streams in said one device and for priming a second of said devices for later establishment of similar electron streams in said second device, and means responsive to a second of said pulses to establish said electron streams in said second device and to disestablish the electron streams in said first-mentioned device.

15. In combination, a plurality of interconnected vacuum electron discharge devices, each of said devices including a pair of electrodes between which an electron stream may be established and a secondary electron emission of electrode, means connected to one of said pair of electrodes of one of said devices for establishing secondary electron emission in said device and for priming a second of said devices for establishment of secondary electron emission in said second device,,and means for establishing secondary electron emission in said second device and for disestablishing the secondary electron emission in said first-mentioned device.

I 16. In combination, a plurality of interconnected vacuum electron discharge devices, each of said devices including a pair of electrodes between which an electron stream may be established and a secondary electron emission electrode, means connected to one of said pair of electrodes of one of said devices for establishing secondary electron emission in said device and for priming a second of said devices for establishment of secondary electron emission insaid second device, and means for establishing secondary electron emission in said second device and for simultaneously disestablishing the. secondary electron emission in said first-mentioned device.

17. In combination, a plurality of interconnected vacuum electron discharge devices, each of said devices including a pair of electrodes between which an electron stream maybe established and a secondary electron emission electrode, means connected to one of said pair of electrodes of one of said devices and to the secondary electron emission-electrode-ofsaid one device for establishing secondary electron emission in said device and for priminga-second-of said devices for establishment of secondary electron emission in said second device, and means for establishing secondary electron emission in said second device and for disestablishing the secondary electron emission in said first-mentioned device.

18. In combination, a plurality of interconnected vacuum electron discharge devices, each of said devices including a pair of electrodes between which an electron stream may be established and a secondary electron emission electrode, means connected to one of said pair of electrodes of one of said devices for establishin secondary electron emission in said device and for priming a second of said devices for establishment of secondary electron emission in said second device, and means for simultaneously establishing secondary electron emission in said second device, for indicating the establishment of secondary electron emission in said second device, and for disestablishing the secondary electron emission in said first-mentioned device.

ALBERT M. SKELLETT. 

